Barrier materials for display devices

ABSTRACT

Described herein are apparatus comprising one or more silicon-containing layers and a metal oxide layer. Also described herein are methods for forming one or more silicon-containing layers to be used, for example, as passivation layers in a display device. In one particular aspect, the apparatus comprises a transparent metal oxide layer, a silicon oxide layer and a silicon nitride layer. In this or other aspects, the apparatus is deposited at a temperature of 350° C. or below. The silicon-containing layers described herein comprise one or more of the following properties: a density of about 1.9 g/cm 3  or greater; a hydrogen content of about 4×10 22  cm −3  or less, and a transparency of about 90% or greater at 400-700 nm as measured by a UV-visible light spectrometer.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application claims the priority benefit of prior U.S.Provisional Patent Application Ser. No. 61/609,045 filed Mar. 9, 2012.

BACKGROUND OF THE INVENTION

Display devices have been in production for a wide range of electronicapplications, such as flat screen televisions (TV), flat monitors,mobile phone, MP3 players, electronic book or eBook readers, andpersonal digital assistants (PDAs) and the like. The display devices aredesigned for producing a desired image by applying an electric field toa liquid crystal that fills a gap between two substrates and has ananisotropic dielectric constant that controls the intensity of thedielectric field. By adjusting the amount of light transmitted throughthe substrates, the light and image intensity, image quality, and/orpower consumption may be efficiently controlled.

Thin film transistors (TFTs) for flat panel displays benefit from alower processing temperature (e.g., 350° C. or below) so thatalternative substrates that are lighter and less expensive than thepresently used substrate or glass can be used. Various display devices,such as active matrix liquid crystal display (AMLCD) or an active matrixorganic light emitting diodes (AMOLED), can be employed as light sourcesfor display devices which use touch screen panels. Amorphous oxidesemiconductors (AOS), transparent amorphous oxide semiconductor (TAOS)or metal oxide materials are fast emerging as replacement materials forTFTs that provides higher performance than glass be improving thedevice's electrical performance and are processable at lowertemperatures. Examples of AOS, transparent amorphous oxide semiconductor(TAOS) or metal oxide materials that are being considered asreplacements for TFTs include Indium Gallium Zinc Oxide (IGZO), a-IGZO(amorphous gallium indium zinc oxide), Indium Tin Zinc Oxide (ITZO),Aluminum Indium Oxide (AlInOx), Zinc Tin Oxide (ZTO), Zinc Oxynitride(ZnON), Magnesium Zinc Oxide, zinc oxide (ZnO) and variations thereof.Despite their advantages over traditional materials, these materialshave a temperature processing limitation of about 350° C. or less.Further, these films may be deposited onto plastic substrates whichlower their temperature processing limitation to about 200° C.Additionally, certain AOS, TAOS, or metal oxide materials may be damagedby the presence of hydrogen atoms in adjacent passivation, gateinsulating layers, or both by reacting with the transparent amorphousoxide semiconductor (TAOS) or metal oxide materials, thereby resultingin current leakage or other types of device failure.

The reference “Influence of Passivation Layers on Characteristics ofa-InGaZnO Thin-Film Transistors”, Liu et al., Electron Device Letters,IEEE, Vol. 32(2), (20110, pp. 161-63 (“Liu et al.”), investigated theeffect of deposition conditions of a dual passivation layer consistingof silicon oxide and silicon nitride atop on the threshold voltage (Vt)of the a-InGaZnO TFT. The test structure used in Liu et al. consisted ofa p-type silicon wafer which had a silicon substrate that served as thegate electrode, a 200 nanometer (nm) thick thermally grown silicondioxide layer which acted as the gate insulator layer, a 45 nm thicksource/drawn (Al) electrodes adjacent a 50 nm thick a-IGZO channellayer. The Al electrodes and a-IGZO layer was topped with a dualpassivation layer consisting of a 30 nm silicon oxide layer and a 180 nmthick silicon nitride layer. The silicon oxide and silicon nitride filmswere deposited by plasma enhanced chemical vapor deposition (PECVD) at200° C. using SiH₄/N₂O/N₂ and 250° C. using SiH₄/NH₃/N₂, respectively.The threshold voltage (VT) of the TFTs shifted markedly as a result ofthe mechanical stress induced by the passivation layers above. Byadjusting the deposition parameters of the silicon nitride top layerduring the passivation process, the performance of the TFTs can bemodulated. The optimized a-InGaZnO TFTs after dual passivation exhibitedthe following characteristics: a field-effect mobility of 11.35 cm²/V·s,a threshold voltage of 2.86 V, a subthreshold swing of 0.5V, and anon-off ratio of 10⁸.

The reference “Impact of Hydrogenation of ZnO TFTs by Plasma-DepositedSilicon Nitride Gate Dielectric”, Remashan et al., IEEE Transactions onElectronic Devices, Vol. 55, No. 10 (October 2008), pp. 2736-43,describes the effects of depositing by PECVD a silicon nitride layerhaving variable refractive indices for use as a gate dielectric layer ona zinc oxide (ZnO) TFT with a bottom gate configuration. The authorsstated that hydrogenation is one of the methods in which performance ofZnO TFTs can be improved because hydrogen acts as a defect passivatorand a shallow n-type dopant in ZnO materials. In Remashan et al., thefour silicon nitride films were deposited via PECVD at a pressure of 650mTorr, temperature of 300° C., and power of 30 W but using differentmolar ratios of silane relative to ammonia and nitrogen to providesilicon nitride films having different refractive indices (e.g., 2.39,2.26, 1.92, and 1.80) and dielectric constants (7.9, 8.4, 6.7, and 6.1).The authors found that the amongst all of the TFTs, the device havingthe highest refractive index silicon nitride film or SiN_2.39 exhibitedthe best performance in terms of field-effect mobility, subthresholdslope, and maximum interface state density. An analysis of the secondaryion mass spectroscopy (SIMS) data showed that the amount of hydrogenpresent at the ZnO/insulator interface and in the ZnO channels for theTFT structures using a SiN_2.39 was much higher than those structuresusing a SiN_1.80. Therefore, the authors have concluded that theenhanced performance of the TFTs using the SiN_2.39 films is attributedto the incorporation of hydrogen into the ZnO channel and ZnO/insulatorinterface from the SiN_2.39.

The reference “Circuits Using Uniform TFTs Based on AmorphousIn—Ga—Zn—O”, Ryo Hayashi et al., Journal of the Society for InformationDisplay, Vol. 15(11), 2007, pp. 915-92 discloses high-performance andexcellent-uniformity thin-film transistors (TFTs) having bottom-gatestructures fabricated using an amorphous indium-gallium-zinc-oxide(IGZO) film and an amorphous-silicon dioxide film as the channel layerand the gate insulator layer, respectively. All of the 94 TFTsfabricated with an area 1 cm² show almost identical transfercharacteristics: the average saturation mobility is 14.6 cm²/(V-sec)with a small standard deviation of 0.11 cm²/(V-sec). A five-stagering-oscillator composed of these TFTs operates at 410 kHz at an inputvoltage of 18 V. Pixel-driving circuits based on these TFTs are alsofabricated with organic light-emitting diodes (OLED) which aremonolithically integrated on the same substrate. It was demonstratedthat light emission from the OLED cells can be switched and modulated bya 120-Hz ac signal input. Amorphous-IGZO-based TFTs are prominentcandidates for building blocks of large-area OLED-display electronics.

The reference, “Stability and High-Frequency Operation of AmorphousIn—Ga—Zn—O Thin-Film Transistors with Various Passivation Layers”, KenjiNomura et al., Thin Solid Films, doi:10.1016/j.tsf.2011.10.068 (2011),investigated the stability of amorphous In—Ga—Zn—O (a-IGZO) thin-filmtransistors (TFTs) focusing on the effects of passivation layermaterials (Y₂O₃, Al₂O₃, HfO₂, and SiO₂) and thermal annealing. Positivebias constant current stress (CCS), negative bias stress without lightillumination (NBS), and negative bias light illumination stress (NBLS)were examined. It was found that Y₂O₃ was the best passivation layermaterial in this study in terms of all the stability tests if thechannel was annealed prior to the passivation formation (post-depositionannealing) and the passivation layer was annealed at 250° C.(post-fabrication annealing). Post-fabrication thermal annealing of theY₂O₃ passivation layer produced very stable TFTs against the CCS and NBSstresses and eliminated sub gap photoresponse up to the photon energy of2.9 eV. Even for NBLS with 2.7 eV photons, the threshold voltage shiftis suppressed well to −4.4 V after 3 hours of testing. These resultsprovide the following information; (i) passivation removes the surfacedeep subgap defects in a-IGZO and eliminates the subgap photoresponse,but (ii) the bulk defects in a-IGZO should be removed prior to thepassivation process. The Y₂O₃-passivated TFT is not only stable forthese stress conditions, but is also compatible with high-frequencyoperation with the current gain cut-off frequency of 91 kHz, which isconsistent with the static characteristics.

US Publ. No. 2012/045904 (“the '904 Publ.”) discloses methods of forminga hydrogen free silicon containing layer in TFT devices. The hydrogenfree silicon containing layer may be used as a passivation layer, a gatedielectric layer, an etch stop layer, or other suitable layers in TFTdevices, photodiodes, semiconductor diode, light-emitting diode (LED),or organic light-emitting diode (OLED), or other suitable displayapplications. In one embodiment, a method for forming a hydrogen freesilicon containing layer in a thin film transistor includes supplying agas mixture comprising a hydrogen free silicon containing gas and areacting gas into a plasma enhanced chemical vapor deposition chamber,wherein the hydrogen free silicon containing gas is selected from agroup consisting of SiF₄, SiCl₄, Si₂Cl₆, and forming a hydrogen freesilicon containing layer on the substrate in the presence of the gasmixture.

US Publ. No. 2010/059756 (“'the 756 Publ.”) disclose a thin filmtransistor (TFT). The TFT may include an intermediate layer between achannel and a source and drain. An increased off current which may occurto a drain area of the TFT is reduced due to the intermediate layerwhich is formed of amorphous silicon (a-Si), poly-Si, germanium (Ge), orsilicon-germanium (SiGe).

Therefore, there is a need for a display device and method tomanufacture same that provides one or more of the following advantages:good electrical properties meaning that it retains its semiconductivenature after processing; low processing temperatures (e.g., 350° C. orless) reduced hydrogen content; improved electrical performance; andlong term stability.

BRIEF SUMMARY OF THE INVENTION

Described herein are apparatus comprising one or more silicon-containinglayers and a transparent metal oxide. Also described herein are methodsfor forming one or more silicon-containing layers to be used, forexample, as passivation layers in a display device.

The low temperature silicon-containing films have at one least one ormore of the following properties: a density of about 1.9 grams per cubiccentimeter (g/cm³ or g/cc) or greater; a hydrogen content of 4×10²² cm⁻³or less; a transparency of 90% or greater at 400-700 nm as measured by aUV-visible light spectrometer; and combinations thereof. In oneparticular embodiment, the silicon-containing film are silicon nitrideor silicon oxynitride have at one least one or more of the followingproperties: a density of about 2.2 g/cm³ or greater; a hydrogen contentof about 4×10²² cm⁻³ or lower, and a transparency of about 90% orgreater at 400-700 nm as measured by a UV-visible light spectrometer. Inone aspect, there is provided an apparatus comprising: a substratecomprising a metal oxide layer; and a silicon nitride layer depositedonto at least a portion of the metal oxide wherein the silicon nitridelayer comprises a density of about 2.4 g/cm³ or greater and a hydrogencontent of about 4×10²² cm⁻³ or less as measured by an analyticaltechnique such as Fourier transform infrared spectroscopy (FT-IR),Rutherford Backscattering Spectrometry (RBS), or hydrogen forwardscattering (HFS) or other method. In this or other embodiments, thesilicon nitride layer has a transparency of about 90% or greater at400-700 nanometers are measured by UV-visible light spectrometry.

In a further aspect, there is provided an apparatus comprising: asubstrate comprising a metal oxide layer; a silicon nitride layerdeposited onto at least a portion of the metal oxide wherein the siliconnitride layer comprises a density of about 2.4 g/cm³ or greater, ahydrogen content of 4×10²² cm⁻³ or less, and a transparency of about 90%or greater at 400-700 nanometers are measured by UV-visible lightspectrometry; and a silicon oxide layer deposited between the metaloxide layer and the silicon nitride layer wherein the silicon oxidelayer comprises a density of about 2.2 g/cm³ or greater.

In a still further aspect, there is provided a method for depositing asilicon-containing film on at least one surface of a substrate whereinthe substrate comprises a metal oxide, the method comprising:

providing the at least one surface of the substrate in a reactionchamber; introducing into the reaction chamber a silicon precursorselected from the group consisting of:

-   -   a. trisilylamine (TSA);    -   b. a dialkylaminosilane having a formula of R¹R²NSiH₃ wherein R¹        is independently selected from the group consisting of a C₁₋₁₀        linear or branched alkyl group; a C₄ to C₁₀ cyclic alkyl group;        a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl group; and a C₆        to C₁₀ aryl group; R² is independently selected from a C₁₋₁₀        linear or branched alkyl group; a C₄ to C₁₀ cyclic alkyl group;        a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl group; and a C₆        to C₁₀ aryl group and wherein R¹ and R² are linked to form a        ring or R¹ and R² are not linked to form a ring;    -   c. an alkylsilane having a formula of R¹ _(n)R² _(m)SiH_(4-m-n)        wherein R¹ is independently selected from the group consisting        of a C₁₋₁₀ linear or branched alkyl group; a C₄ to C₁₀ cyclic        alkyl group; a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl        group; and a C₆ to C₁₀ aryl group; R² is independently selected        from a C₁₋₁₀ linear or branched alkyl group; a C₄ to C₁₀ cyclic        alkyl group; a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl        group; and a C₆ to C₁₀ aryl group and wherein R¹ and R² are        linked to form a ring or R¹ and R² are not linked to form a        ring; m is 0, 1, 2, 3, 4; and n is 1, 2, 3;    -   d. an alkylalkoxysilane having a formula of R¹        _(n)(OR²)_(m)SiH_(4-m-n) wherein R¹ is independently selected        from the group consisting of a C₁₋₁₀ linear or branched alkyl        group; a C₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl        group; a C₃ to C₁₂ alkynyl group; and a C₆ to C₁₀ aryl group; R²        is independently selected from a C₁₋₁₀ linear or branched alkyl        group; a C₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl group        a C₃ to C₁₂ alkynyl group; and a C₆ to C₁₀ aryl group and        wherein R¹ and R² are linked to form a ring or R¹ and R² are not        linked to form a ring; m is 1, 2, 3, or 4; and n is 0, 1, 2 or        3;    -   e. an organoaminosilanes having a formula of        (R¹R²N)_(n)SiH^(4-n) wherein R¹ is independently selected from        the group consisting of a C₁₋₁₀ linear or branched alkyl group;        a C₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl group; a C₃        to C₁₂ alkynyl group; and a C₆ to C₁₀ aryl group; R² is        independently selected from a C₁₋₁₀ linear or branched alkyl        group; a C₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl        group; a C₃ to C₁₂ alkynyl group; and a C₆ to C₁₀ aryl group and        wherein R¹ and R² are linked to form a ring or Wand R² are not        linked to form a ring; and n is 2, 3, or 4;    -   f. an isocyanatosilane selected from the group consisting of        tetra(isocynato)silane and tri(isocynato)silane;    -   g. an alkylazidosilanes having the formula of R¹R²R³SiN₃ wherein        R¹, R², and R³ are independently selected from the group        consisting of a C₁₋₁₀ linear or branched alkyl group; a C₄ to        C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂        alkynyl group; and a C₆ to C₁₀ aryl group;    -   h. an alkylbridged disilanes having the formula of        (R¹R²R³Si)₂(CH₂)_(n), R¹R²R³SiN₃ wherein R¹, R², and R³ are        independently selected from the group consisting of a C₁₋₁₀        linear or branched alkyl group; a C₄ to C₁₀ cyclic alkyl group;        a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl group; and a C₆        to C₁₀ aryl group; and n=1, 2, 3;    -   i. an alkoxysilane having a formula of Si(OR¹)₄ wherein R¹ is        independently selected from the group consisting of a C₁₋₁₀        linear or branched alkyl group; a C₄ to C₁₀ cyclic alkyl group;        a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl group; and a C₆        to C₁₀ aryl group; and combinations thereof;        introducing into the reaction chamber an source selected from an        oxygen source, a nitrogen-containing source, or a combination        thereof; and depositing via a vapor deposition process the thin        silicon containing layer on the at least one surface of the        substrate at one or more temperatures ranging from about 25° C.        to 350° C.; wherein the vapor deposition process is selected        from a group consisting of chemical vapor deposition (CVD),        plasma enhanced chemical vapor deposition (PECVD), cyclic        chemical vapor deposition (CCVD), plasma enhanced cyclic        chemical vapor deposition (PECCVD, atomic layer deposition        (ALD), and plasma enhanced atomic layer deposition (PEALD).

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows the relationship between density (g/cm³) and hydrogen (H)content (as measured by XPS) for the various silicon-containing filmsdeposited onto silicon substrates and provided in Examples 1 andComparative Examples 2 through 7. FIG. 1 shows that the highest densitylayers were obtained by the TSA precursors.

FIG. 2 shows the relationship between density and H-content for filmsdeposited using TSA precursor at different temperature ranges (150-325°C.) where the diamonds on the Figure relate to density and the squareson the Figure relate to hydrogen content

FIG. 3 shows the relationship between density and H-content for thefilms deposited at 300° C. using TSA as the precursor in Example 1wherein the squares indicate data that was obtained using LF power andthe diamonds indicate data that was obtained without LF power

FIG. 4 provides a comparison of the moisture barrier performance for 100nm thick silicon-containing films deposited from the followingprecursors: (A) (shown as diamonds on Figure) trisilylamine and NH₃(density=2.36 g/cm³); (B) (shown as triangles on Figure)di-isopropylaminosilane and NH₃ (density=2.11 g/cm³) (C) (shown assquares on the Figure) dimethyldiethoxysilane and H₂ (density=1.95g/cm³); and (D) (shown as circles on the Figure) trimethylsilane and NH₃(density=1.88 g/cm³).

FIG. 5 provides a comparison of moisture barrier performance for 82 nmthick and 100 nm thick films deposited from TEOS and O₂ (or wafers 16and 17 which had a density=2.25 g/cm³) or trisilylamine and NH₃ (orwafers 6, 7, and 8 which had a density=2.52 g/cm³), respectively.

FIG. 6 provides an exemplary device structure that was used to evaluateimpact on surface recombination velocity in Example 9.

FIG. 7 provides the surface recombination velocity observed for HighResistivity Float Zone Silicon Passivated with TSA+NH₃ nitride andvarying thickness of TEOS+O₂ PECVD Silicon Oxide deposited between thesilicon substrate and the silicon nitride and described in Example 9.

FIG. 8a through 8e provides exemplary structures that were used tomeasure the impact of passivation layers on IGZO resistivity and aredescribed in Example 10.

FIGS. 9a and 9b provide examples of the single passivation layer anddouble passivation layer embodiments of the apparatus described herein.

FIG. 10 provides the relationship between stress measured in megapascalsand time measured in hours between different exemplary devices

DETAILED DESCRIPTION OF THE INVENTION

Apparatuses comprising transparent metal oxides such as, for example,IGZO-based TFTs, are being implemented for mobile displays. In oneparticular embodiment wherein the composition of the transparent metaloxide comprises IGZO, the thermal budget, which relates to the upperlimit of the processing temperature that the apparatus can be subjectedto, requires that one or more passivation films be deposited at one ormore temperatures of 300° C. or below. In this or other embodiments, theone or more passivation layers provide good hermeticity, which isdescribed herein as impervious to a fluid such as, without limitation agas, a liquid or combinations thereof, by having a density of about 2.4grams per cubic centimeter (g/cm³ or g/cc) or higher and a hydrogencontent of 4×10²² cm⁻³ or lower or 2×10²² cm⁻³ or lower. The prior artdescribes dual layer structures wherein silane gas (SiH₄) is used toform SiN:H and SiO₂ films to passivate the a-Si TFTs underlyingstructure. While these SiN:H and SiO₂ films can be formed attemperatures below 300° C., the density and H-content of these filmsdoes not achieve the desired properties needed for passivating theunderlying transparent metal oxide layer when deposited at temperaturesbelow 300° C. In this regard, the desired properties for a siliconcontaining film that can be used as one or more passivation layers for ametal oxide layer in a display device comprise one or more of thefollowing: a deposition temperature of about 350° C. or less; a densityof about 2.4 g/cm³ or higher, a hydrogen content of about 2×10²² cm⁻³ orlower, a transparency of about 90% from 400-700 nm as measured by UV-VisSpectrometer; and combinations thereof.

Described herein is a method to deposit a silicon containing film thatcan be employed as one or more passivation layers for a display devicewhich comprises at least one silicon-containing layer and at least onetransparent metal oxide layer. The term passivation layer could mean,without limitation, a passivation layer, a gate dielectric layer, anetch stop layer, or other suitable layer in a display device such as aTFT device, a OLED device, a LED device or other display applications.The term silicon-containing films as used herein can mean a silicon,amorphous silicon, crystalline silicon, microcrystalline silicon,polycrystalline silicon, stoichiometric or non-stoichiometric siliconnitride, or non-stoichiometric silicon oxide, carbon doped siliconoxide, silicon carbonitride, and silicon oxynitride films. Of theforegoing, the one or more silicon-containing films are comprised ofsilicon oxide, silicon nitride, silicon oxynitride, silicon carboxide,and silicon carboxynitrde. The term “metal oxide” means one or morelayers within the device that is suitable for use in a display device.In this regard, the metal oxide layer exhibits one or more the followingproperties: has requisite transparency for use in a display device,exhibits high electron mobility, and can be manufactured at lowprocessing temperatures (e.g., 350° C. or below or 300° C. or below).Examples of metal oxides include but are not limited to, Indium GalliumZinc Oxide (IGZO), a-IGZO (amorphous indium gallium zinc oxide), IndiumTin Zinc Oxide (ITZO), Aluminum Indium Oxide (AlInOx), Zinc Tin Oxide(ZTO), Zinc Oxynitride (ZnON), Magnesium Zinc Oxide, zinc oxide (ZnO),InGaZnON, ZnON, ZnSnO, CdSnO, GaSnO, TiSnO, CuAlO, SrCuo, LaCuOS, GaN,InGaN, AlGaN or InGaAlN and combinations thereof.

In addition to the one or more passivation layers and metal oxide layer,the display device may further include, without limitation, gateinsulation layers, gate electrode layer(s), source drain layer(s), andother layers. The apparatus and method described herein may be used todeposit the at least one silicon-containing and metal oxide layer ontoat least a portion of a substrate. Examples of suitable substratesinclude but are not limited to, glass, plastics, stainless steel,organic or polymer films, silicon, SiO₂, Si₃N₄, OSG, FSG, siliconcarbide, hydrogenated silicon carbide, silicon nitride, hydrogenatedsilicon nitride, silicon carbonitride, hydrogenated siliconcarbonitride, boronitride, antireflective coatings, photoresists,organic polymers, porous organic and inorganic materials, metals such ascopper, aluminum, chromium, molybdenum and gate electrodes such as, butnot limited to, TiN, Ti(C)N, TaN, Ta(C)N, Ta, W, WN, ITO or other gateelectrodes. The silicon-containing films are compatible with a varietyof subsequent processing steps such as, for example, chemical mechanicalplanarization (CMP) and anisotropic etching processes. In certainembodiments, the silicon-containing layer described herein has adielectric constant of that ranges from about 4.0 to about 5.5 or fromabout 4.0 to about 4.5.

In one embodiment 10 of the apparatus described herein and shown in FIG.9a , the silicon-containing film is deposited as a single passivationlayer 30 onto at least a portion of a metal oxide 20 that can be use,for example, in a display device. In an alternative embodiment 100 ofthe apparatus described herein and shown in FIG. 9b , thesilicon-containing film is deposited onto one or more silicon-containingfilms above the metal oxide layer 120 which is shown as passivationlayer 2, or 140 on FIG. 9b , and passivation layer 1, or 130 on FIG. 9b, to provide a double passivation layer structure or multi-layeredpassivation layer structure. In one embodiment, the silicon-containingfilms in the double passivation or multi-layered are different types ofsilicon-containing films. Alternatively, the silicon-containing films inthe double or multi-layered structures can be the same types ofsilicon-containing films but alternated in a variety of ways, such aswithout limitation, SixOy, SiwNz, SixOy, and SiwNz; SixOy, SixOy, andSiwNz; SixOy, SiwNz, and SiwNz; and various combinations thereof. Whilethe exemplary structures shown in FIGS. 9a and 9b show the one or morepassivation layers deposited onto at least a portion of the metal oxidefilm, it is understood that the one or more layers are not limited toarrangement of layers depicted in FIGS. 9a and 9b and may be above orbelow metal oxide layer and one or more passivation layer(s),sandwiched, imbedded, surrounded, have intervening layers which are notsilicon-containing, or any other spatial relationships with respect toeach other and are subsequently not limited thereto.

In one particular embodiment, the display device comprises at least twopassivation layers deposited onto the metal oxide layer such as thatshown in FIG. 9b wherein the passivation layers comprise: a siliconoxide or layer 140 as passivation layer 2 and a silicon nitride as layer130 or passivation layer 1. In one particular embodiment of theapparatus shown in 9 b, the metal oxide layer comprises IGZO and the atleast two passivation layers act as a barrier to protect the IGZO filmfrom diffusion of atmospheric impurities (e.g., be hermetic) while notimpacting to any great significance the resistivity of the IGZO filmpost treatment. In this particular embodiment, the apparatus comprises ahigh density silicon nitride film (e.g., having a density of 2.4 g/cm³or greater) as passivation layer 1 and is deposited by the precursortrisilylamine (TSA) and ammonia (NH₃) at one or more temperatures thatrange from about 80° C. to about 400° C. The device further comprises asilicon oxide film as passivation layer 2 to prevent the diffusion ofactive hydrogen contained in the silicon nitride to the IGZO locatedbeneath the oxide. The silicon oxide film can be deposited at one ormore temperatures ranging from 80° C. to 400° C. It is desirable thatthe precursor selected and the deposition process conditions impart aminimum of hydrogen, hydroxyl groups, or other moieties such as carbon,hydrocarbons or other functional groups which can react with the metaloxide layer such as IGZO. In one particular embodiment, passivationlayer 2 or 140 in FIG. 9b is a low temperature deposited (e.g., 300° C.or less) silicon oxide film which is deposited from triethylsilane,diethylsilane, or tetraethoxysilane and has one or more of the followingproperties: a thickness of about 2 nm to about 200 nm, a density ofabout 2.2 g/cm³ or greater, and a hydrogen content of about 5 atomicpercent or less. In this or other embodiments, the passivation layer 2or 140 in FIG. 9b is deposited from a silicon-containing precursor whichdoes not contain a Si—H group because it is known that Si—H may reactwith the metal oxide, thus damaging the electric property of the metaloxide layer. While not being bound to theory, for apparatus having twoor more passivation layers comprising a silicon oxide and siliconnitride, the applicants believe that the selection of the silicon oxideprecursor and its deposition parameters and the silicon nitride and itsdeposition parameters are important to ensure that the attributes of oneor more passivation layers do not adversely impact the resistivity ofthe metal oxide layer.

In one particular embodiment, the apparatus of display device describedherein comprises at least one passivation layer that is deposited usingthe precursor trisilylamine (TSA) and is a silicon nitride or a siliconoxynitride film. In this embodiment, the passivation layer is depositedusing a PECVD process at a deposition temperature of 300° C. employingtrisilylamine TSA and provides a film density of 2.5 g/cm³ or greaterand a hydrogen content of 2×10²² cm⁻³ or less. In a further embodiment,described herein is an apparatus comprising a TSA-deposited siliconnitride film which was deposited via PECVD at a even lower temperaturedeposition temperature or 200° C. and has a density of about 2.4 g/cm³or greater. In both of the above embodiments, the TSA-deposited siliconnitride films provide a transparency requirements of 90% transparency orgreater from 400-700 nm as measured by UV-visible light spectrometer tobe suitable for display device applications. Further, in both of theseembodiments, the apparatus has at least one or more passivation layersthat allows the metal oxide layer, such as a metal oxide layercomprising IGZO, to have a resistance that is semiconductive (e.g.,having a resistance of from 1×10⁴ to 1×10⁵ Ohms/square (Ω/□)). Theapparatus described herein retains this resistance range or remainssemiconductive even after it has been exposed to high temperature andhigh humidity or 85° C. and 85% humidity cycles.

As previously mentioned, in addition to the silicon nitride passivationlayer, in one embodiment of the apparatus described herein, theapparatus further comprises a silicon oxide layer. This silicon oxidelayer, like the silicon nitride layer, has at least one or more of thefollowing properties: a thickness of about 2 nm to about 200 nm, adensity of about 2.2 g/cm³ or greater, and a hydrogen content of about 5atomic percent or less. In certain embodiments, the precursor used todeposit the silicon oxide film does not have a Si—H bond such astetraalkoxysilane (TEOS).

The method used to form the one or more silicon-containing film(s) orlayer(s) and the metal oxide layer(s) are referred to herein as adeposition process. Examples of suitable deposition processes for themethod disclosed herein include, but are not limited to, chemical vapordepositions (CVD), cyclic CVD (CCVD), MOCVD (Metal Organic CVD), thermalchemical vapor deposition, plasma enhanced chemical vapor deposition(“PECVD”), high density PECVD, photon assisted CVD, plasma-photonassisted (“PPECVD”), cryogenic chemical vapor deposition, chemicalassisted vapor deposition, hot-filament chemical vapor deposition, CVDof a liquid polymer precursor, deposition from supercritical fluids, andlow energy CVD (LECVD). In certain embodiments, the films are depositedvia atomic layer deposition (ALD), plasma enhanced ALD (PEALD) or plasmaenhanced cyclic CVD (PECCVD) process. As used herein, the term “chemicalvapor deposition processes” refers to any process wherein a substrate isexposed to one or more volatile precursors, which react and/or decomposeon the substrate surface to produce the desired deposition. As usedherein, the term “atomic layer deposition process” refers to aself-limiting (e.g., the amount of film material deposited in eachreaction cycle is constant), sequential surface chemistry that depositsfilms of materials onto substrates of varying compositions. Although theprecursors, reagents and sources used herein may be sometimes describedas “gaseous”, it is understood that the precursors can also be liquid orsolid which are transported with or without an inert gas into thereactor via direct vaporization, bubbling or sublimation. In some case,the vaporized precursors can pass through a plasma generator. In oneembodiment, the one or more films is deposited using an ALD process. Inanother embodiment, the one or more films is deposited using a CCVDprocess. In a further embodiment, the one or more films is depositedusing a thermal CVD process. The term “reactor” as used herein, includeswithout limitation, reaction chamber or deposition chamber.

In certain embodiments, the method disclosed herein avoids pre-reactionof the precursors by using ALD or CCVD methods that separate theprecursors prior to and/or during the introduction to the reactor. Inthis connection, deposition techniques such as ALD or CCVD processes areused to deposit the film. In one embodiment, the film is deposited viaan ALD process by exposing the substrate surface alternatively to theone or more the silicon-containing precursor, oxygen source,nitrogen-containing source, or other precursor or reagent. Film growthproceeds by self-limiting control of surface reaction, the pulse lengthof each precursor or reagent, and the deposition temperature. However,once the surface of the substrate is saturated, the film growth ceases.

The silicon-containing precursors using for depositing the one or moresilicon-containing films or layers are selected from the groupconsisting of:

-   -   a. trisilylamine (TSA);    -   b. a dialkylaminosilane having a formula of R¹R²NSiH₃ wherein R¹        is independently selected from the group consisting of a C₁₋₁₀        linear or branched alkyl group; a C₄ to C₁₀ cyclic alkyl group;        a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl group; and a C₆        to C₁₀ aryl group; R² is independently selected from a C₁₋₁₀        linear or branched alkyl group; a C₄ to C₁₀ cyclic alkyl group;        a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl group; and a C₆        to C₁₀ aryl group and wherein R¹ and R² are linked to form a        ring or R¹ and R² are not linked to form a ring;    -   c. an alkylsilane having a formula of R¹⁰R² _(m)SiH_(4-m-n)        wherein R¹ is independently selected from the group consisting        of a C₁₋₁₀ linear or branched alkyl group; a C₄ to C₁₀ cyclic        alkyl group; a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl        group; and a C₆ to C₁₀ aryl group; R² is independently selected        from a C₁₋₁₀ linear or branched alkyl group; a C₄ to C₁₀ cyclic        alkyl group; a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl        group; and a C₆ to C₁₀ aryl group and wherein R¹ and R² are        linked to form a ring or R¹ and R² are not linked to form a        ring; m is 0, 1, 2, 3, 4; and n is 1, 2, 3;    -   d. an alkylalkoxysilane having a formula of R¹        _(n)(OR²)_(m)SiH_(4-m-n) wherein R¹ is independently selected        from the group consisting of a C₁₋₁₀ linear or branched alkyl        group; a C₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl        group; a C₃ to C₁₂ alkynyl group; and a C₆ to C₁₀ aryl group; R²        is independently selected from a C₁₋₁₀ linear or branched alkyl        group; a C₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl        group; a C₃ to C₁₂ alkynyl group; and a C₆ to C₁₀ aryl group and        wherein R¹ and R² are linked to form a ring or R¹ and R² are not        linked to form a ring; m is 1, 2, 3, or 4; and n is 0, 1, 2 or        3;    -   e. an organoaminosilanes having a formula of        (R¹R²N)_(n)SiH_(4-n) wherein R¹ is independently selected from        the group consisting of a C₁₋₁₀ linear or branched alkyl group;        a C₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl group; a C₃        to C₁₂ alkynyl group; and a C₆ to C₁₀ aryl group; R² is        independently selected from a C₁₋₁₀ linear or branched alkyl        group; a C₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl        group; a C₃ to C₁₂ alkynyl group; and a C₆ to C₁₀ aryl group and        wherein R¹ and R² are linked to form a ring or R¹ and R² are not        linked to form a ring; and n is 2, 3, or 4;    -   f. an isocyanatosilane selected from the group consisting of        tetra(isocynato)silane and tri(isocynato)silane;    -   g. an alkylazidosilanes having the formula of R¹R²R³SiN₃ wherein        R¹, R², and R³ are independently selected from the group        consisting of a C₁₋₁₀ linear or branched alkyl group; a C₄ to        C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂        alkynyl group; and a C₆ to C₁₀ aryl group;    -   h. an alkylbridged disilanes having the formula of        (R¹R²R³Si)₂(CH₂)_(n), R¹R²R³SiN₃ wherein R¹, R², and R³ are        independently selected from the group consisting of a C₁₋₁₀        linear or branched alkyl group; a C₄ to C₁₀ cyclic alkyl group;        a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl group; and a C₆        to C₁₀ aryl group; and n=1, 2, 3;    -   i. an alkoxysilane having a formula of Si(OR¹)₄ wherein R¹ is        independently selected from the group consisting of a C₁₋₁₀        linear or branched alkyl group; a C₄ to C₁₀ cyclic alkyl group;        a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl group; and a C₆        to C₁₀ aryl group; and combinations thereof.

In another embodiment, the one or more silicon-containing layer(s) isdeposited using a deposition process described herein from a compositioncomprising trisilylamine (TSA) and one or more of the silicon-containingprecursors selected from the group consisting of:

-   -   a. a dialkylaminosilane having a formula of R¹R²NSiH₃ wherein R¹        is independently selected from the group consisting of a C₁₋₁₀        linear or branched alkyl group; a C₄ to C₁₀ cyclic alkyl group;        a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl group; and a C₆        to C₁₀ aryl group; R² is independently selected from a C₁₋₁₀        linear or branched alkyl group; a C₄ to C₁₀ cyclic alkyl group;        a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl group; and a C₆        to C₁₀ aryl group and wherein R¹ and R² are linked to form a        ring or R¹ and R² are not linked to form a ring;    -   b. an alkylsilane having a formula of R¹ _(n)R² _(m)SiH_(4-m-n)        wherein R¹ is independently selected from the group consisting        of a C₁₋₁₀ linear or branched alkyl group; a C₄ to C₁₀ cyclic        alkyl group; a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl        group; and a C₆ to C₁₀ aryl group; R² is independently selected        from a C₁₋₁₀ linear or branched alkyl group; a C₄ to C₁₀ cyclic        alkyl group; a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl        group; and a C₆ to C₁₀ aryl group and wherein R¹ and R² are        linked to form a ring or R¹ and R² are not linked to form a        ring; m is 0, 1, 2, 3, 4; and n is 1, 2, 3;    -   c. an alkylalkoxysilane having a formula of R¹        _(n)(OR²)_(m)SiH_(4-m-n) wherein R¹ is independently selected        from the group consisting of a C₁₋₁₀ linear or branched alkyl        group; a C₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl        group; a C₃ to C₁₂ alkynyl group; and a C₆ to C₁₀ aryl group; R²        is independently selected from a C₁₋₁₀ linear or branched alkyl        group; a C₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl        group; a C₃ to C₁₂ alkynyl group; and a C₆ to C₁₀ aryl group and        wherein R¹ and R² are linked to form a ring or R¹ and R² are not        linked to form a ring; m is 1, 2, 3, or 4; and n is 0, 1, 2 or        3;    -   d. an organoaminosilanes having a formula of        (R¹R²N)_(n)SiH_(4-n) wherein R¹ is independently selected from        the group consisting of a C₁₋₁₀ linear or branched alkyl group;        a C₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl group; a C₃        to C₁₂ alkynyl group; and a C₆ to C₁₀ aryl group; R² is        independently selected from a C₁₋₁₀ linear or branched alkyl        group; a C₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl        group; a C₃ to C₁₂ alkynyl group; and a C₆ to C₁₀ aryl group and        wherein R¹ and R² are linked to form a ring or R¹ and R² are not        linked to form a ring; and n is 2, 3, or 4;    -   e. a halosilane selected from the group consisting of        monchlorosilane, dichlorosilane, trichlorosilane,        tetrachlorosilane, and hexachlorosilane;    -   f. an alkoxyaminosilane having a formula of (R¹R²)NSiR³OR⁴OR⁵;        wherein R¹ is independently selected from the group consisting        of a C₁₋₁₀ linear or branched alkyl group; a C₄ to C₁₀ cyclic        alkyl group; a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl        group; and a C₆ to C₁₀ aryl group; R² and R³ are independently        selected from the group consisting of hydrogen, a C₁₋₁₀ linear        or branched alkyl group; a C₄ to C₁₀ cyclic alkyl group; a C₃ to        C₁₂ alkenyl group a C₃ to C₁₂ alkynyl group; and a C₆ to C₁₀        aryl group; R⁴ and R⁵ are independently selected from the group        consisting of a C₁₋₁₀ linear or branched alkyl group; a C₄ to        C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂        alkynyl group; and a C₆ to C₁₀ aryl group; wherein R¹ and R² are        linked to form a ring or R¹ and R² are not linked to form a        ring; and wherein R⁴ and R⁵ are linked to form a ring or R⁴ and        R⁵ are not linked to form a ring;    -   g. an isocyanatosilane selected from the group consisting of        tetra(isocynato)silane and tri(isocynato)silane;    -   h. an alkylazidosilane having the formula of R¹R²R³SiN₃ wherein        R¹, R², and R³ are independently selected from the group        consisting of a C₁₋₁₀ linear or branched alkyl group; a C₄ to        C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂        alkynyl group; and a C₆ to C₁₀ aryl group; and    -   i. an alkylbridged disilane having the formula of        (R¹R²R³Si)₂(CH₂)_(n), R¹R²R³SiN₃ wherein R¹, R², and R³ are        independently selected from the group consisting of a C₁₋₁₀        linear or branched alkyl group; a C₄ to C₁₀ cyclic alkyl group;        a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl group; and a C₆        to C₁₀ aryl group; and n is 1, 2, or 3;    -   j. alkoxysilane having a formula of Si(OR¹)₄ wherein R¹ is        independently selected from the group consisting of a C₁₋₁₀        linear or branched alkyl group; a C₄ to C₁₀ cyclic alkyl group;        a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl group; and a C₆        to C₁₀ aryl group; and combinations thereof.

In the above embodiments for the composition comprising trisilylamineand one or more silicon-containing precursor, the percentage oftrisilylamine in the composition ranges from 0.5 to 99% dependingwhether the deposited silicon-containing film or passivation film canmeet the requirements of targeted display devices. One preferredembodiment is a mixture of trisilylamine with di-iso-propylaminosilanewhich would allow the deposited films to be tuned to meet theapplication requirements. Another preferred embodiment is a mixture oftrisilylamine with diethylsilane as both of which boiling point areclose to each other and allow them to be mixed in liquid form and can bedelivered via direct liquid injection.

Of the foregoing silicon-containing precursors, exemplarydialkylaminosilanes include, but not limited to,di-iso-propylaminosilane, di-sec-butylaminosilane, and2,6-dimethylpiperidinosilane. Exemplary alkylsilanes include, but notlimited to, are diethylsilane (2ES), di(tert-butyl)silane,di(iso-propyl)silane, di(sec-butyl)silane, di(iso-butyl)silane,di(tert-amyl)silane, triethylsilane (3ES), tri(tert-butyl)silane,tri(iso-propyl)silane, tri(sec-butyl)silane, tri(iso-butyl)silane,tri(tert-amyl)silane, tert-butyldiethylsilane, tert-butyldipropylsilane,diethylisopropylsilane, cyclopentylsilane, and phenylsilane. Exemplaryalkylalkoxysilanes include, but not limited to, tetraethoxysilane(TEOS), diethoxydimethylsilane, and tetraethoxysilane. Exemplaryorganoaminosilanes include, but not limited to,tri(dimethylamino)silane, di-isopropylaminosilane, andbis(tert-butylamino)silane. Exemplary alkylazidosilane precursorsinclude, but not limited to, Me₃SiN₃ and Et₃SiN₃. Exemplary alkylbridgedsilanes include, but not limited to, 1,4-disilabutane.

In the formulas above and throughout the description, the term “alkyl”denotes a linear, or branched functional group having from 1 to 10 or 1to 4 carbon atoms. Exemplary alkyl groups include, but are not limitedto, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl,tert-butyl, n-pentyl, iso-pentyl, tert-pentyl, hexyl, isohexyl, andneohexyl. In certain embodiments, the alkyl group may have one or morefunctional groups such as, but not limited to, an alkoxy group, adialkylamino group or combinations thereof, attached thereto. In otherembodiments, the alkyl group does not have one or more functional groupsattached thereto.

In the formulas above and throughout the description, the term “cyclicalkyl” denotes a cyclic functional group having from 3 to 12 or from 4to 10 carbon atoms. Exemplary cyclic alkyl groups include, but are notlimited to, cyclobutyl, cyclopentyl, cyclohexyl, and cyclooctyl groups.

In the formulas above and throughout the description, the term “aryl”denotes an aromatic cyclic functional group having from 6 to 12 carbonatoms. Exemplary aryl groups include, but are not limited to, phenyl,benzyl, chlorobenzyl, tolyl, and o-xylyl.

In the formulas above and throughout the description, the term “alkenylgroup” denotes a group which has one or more carbon-carbon double bondsand has from 2 to 12 or from 2 to 6 carbon atoms. Exemplary alkenylgroups include, but are not limited to, vinyl or allyl groups

In the formulas above and throughout the description, the term “alkynylgroup” denotes a group which has one or more carbon-carbon triple bondsand has from 2 to 12 or from 2 to 6 carbon atoms.

In the formulas above and throughout the description, the term “alkoxy”denotes an alkyl group which has is linked to an oxygen atom (e.g., R—O)and may have from 1 to 12, or from 1 to 6 carbon atoms. Exemplary alkoxygroups include, but are not limited to, methoxy (—OCH₃),ethoxy(—OCH₂CH₃), n-propoxy (—OCH₂CH₂CH₃), and iso-propoxy OCHMe₂).

In certain embodiments, one or more of the alkyl group, alkenyl group,alkynyl group, alkoxy group, and/or aryl group in the formulas above maybe substituted or have one or more atoms or group of atoms substitutedin place of, for example, a hydrogen atom. Exemplary substituentsinclude, but are not limited to, oxygen, sulfur, halogen atoms (e.g., F,Cl, I, or Br), nitrogen, and phosphorous. In other embodiments, one ormore of the alkyl group, alkenyl group, alkynyl group, alkoxy group,and/or aryl in the formula may be unsubstituted.

In certain embodiments, substituents R¹ and R² or substitutents R⁴ andR⁵ (if present) are linked in the above formulas are linked to form aring structure. In certain embodiments, R¹ and R² and/or R⁴ and R⁵ (ifpresent) in the above formulas can be linked together to form a ring. Asthe skilled person will understand, where R¹ and R² are linked togetherto form a ring R¹ will include a bond (instead of a hydrogensubstituent) for linking to R² and vice versa. Thus, in the exampleabove R¹ may be selected from a linear or branched C₁ to C₁₀ alkylenemoiety; a C₂ to C₁₂ alkenylene moiety; a C₂ to C₁₂ alkynylene moiety; aC₄ to C₁₀ cyclic alkyl moiety; and a C₆ to C₁₀ arylene moiety. In theseembodiments, the ring structure can be unsaturated such as, for example,a cyclic alkyl ring or saturated, for example, an aryl ring. In theseembodiments, the ring structure can also be substituted or substituted.In other embodiments, substituent R¹ and R² and substituent R⁴ and R⁵(if present) are not linked.

In certain embodiments, the silicon-containing film or layer depositedusing the methods described herein are formed in the presence of oxygenusing an oxygen source, reagent or precursor comprising oxygen. In oneparticular embodiment such as that depicted in FIG. 9b , thesilicon-containing film 140 or passivation layer 2 comprises siliconoxide and is deposited using the methods described above are formed inthe presence of oxygen using an oxygen source, reagent or precursorcomprising oxygen. An oxygen source may be introduced into the reactorin the form of at least one oxygen source and/or may be presentincidentally in the other precursors used in the deposition process.Suitable oxygen source gases may include, for example, water (H₂O)(e.g., deionized water, purifier water, and/or distilled water), oxygen(O₂), oxygen plasma, ozone (O₃), NO, N₂O, carbon monoxide (CO), carbondioxide (CO₂) and combinations thereof. In certain embodiments, theoxygen source comprises an oxygen source gas that is introduced into thereactor at a flow rate ranging from about 1 to about 2000 square cubiccentimeters (sccm) or from about 1 to about 1000 sccm. The oxygen sourcecan be introduced for a time that ranges from about 0.1 to about 100seconds. In one particular embodiment, the oxygen source comprises waterhaving a temperature of 10° C. or greater. In embodiments wherein thefilm is deposited by an ALD or a cyclic CVD process, the precursor pulsecan have a pulse duration that is greater than 0.01 seconds, and theoxygen source can have a pulse duration that is less than 0.01 seconds,while the water pulse duration can have a pulse duration that is lessthan 0.01 seconds. In yet another embodiment, the purge duration betweenthe pulses that can be as low as 0 seconds or is continuously pulsedwithout a purge in-between. The oxygen source or reagent is provided ina molecular amount less than a 1:1 ratio to the silicon precursor, sothat at least some carbon is retained in the as deposited dielectricfilm.

In certain embodiments, the silicon-containing comprise silicon andnitrogen. In these embodiments, the silicon-containing deposited usingthe methods described herein are formed in the presence ofnitrogen-containing source. In one particular embodiment such as thatdepicted in FIG. 9b , the silicon-containing film 130 or passivationlayer 1 comprises silicon nitride and is deposited using the methodsdescribed above are formed in the presence of nitrogen using a nitrogen,reagent or precursor comprising nitrogen. A nitrogen-containing sourcemay be introduced into the reactor in the form of at least one nitrogensource and/or may be present incidentally in the other precursors usedin the deposition process. Suitable nitrogen-containing source gases mayinclude, for example, ammonia, hydrazine, monoalkylhydrazine,dialkylhydrazine, nitrogen, nitrogen/hydrogen, ammonia plasma, nitrogenplasma, nitrogen/hydrogen plasma, NF₃ and mixture thereof. In oneparticular embodiment, NF₃ is used to reduce the hydrogen content in theresulting films because hydrogen can react with the metal oxide therebyadversely effecting the performance of the display devices. In certainembodiments, the nitrogen-containing source comprises an ammonia plasmaor hydrogen/nitrogen plasma source gas that is introduced into thereactor at a flow rate ranging from about 1 to about 2000 square cubiccentimeters (sccm) or from about 1 to about 1000 sccm. Thenitrogen-containing source can be introduced for a time that ranges fromabout 0.1 to about 100 seconds. In embodiments wherein the film isdeposited by an ALD or a cyclic CVD process, the precursor pulse canhave a pulse duration that is greater than 0.01 seconds, and thenitrogen-containing source can have a pulse duration that is less than0.01 seconds, while the water pulse duration can have a pulse durationthat is less than 0.01 seconds. In yet another embodiment, the purgeduration between the pulses that can be as low as 0 seconds or iscontinuously pulsed without a purge in-between.

The deposition methods disclosed herein may involve one or more purgegases. The purge gas, which is used to purge away unconsumed reactantsand/or reaction byproducts, is an inert gas that does not react with theprecursors. Exemplary purge gases include, but are not limited to, argon(Ar), nitrogen (N₂), helium (He), neon, hydrogen (H₂), and mixturesthereof. In certain embodiments, a purge gas such as Ar is supplied intothe reactor at a flow rate ranging from about 10 to about 2000 sccm forabout 0.1 to 1000 seconds, thereby purging the unreacted material andany byproduct that may remain in the reactor.

The respective step of supplying the precursors, oxygen source, thenitrogen-containing source, and/or other precursors, source gases,and/or reagents may be performed by changing the time for supplying themto change the stoichiometric composition of the resulting dielectricfilm.

Energy is applied to the at least one of the silicon-containingprecursor, oxygen-containing source, nitrogen-containing source,reducing agent, other precursors and/or combination thereof to inducereaction and to form the silicon-containing film or coating on thesubstrate. Such energy can be provided by, but not limited to, thermal,plasma, pulsed plasma, helicon plasma, high density plasma, inductivelycoupled plasma, X-ray, e-beam, photon, remote plasma methods, andcombinations thereof. In certain embodiments, a secondary RF frequencysource can be used to modify the plasma characteristics at the substratesurface. In embodiments wherein the deposition involves plasma, theplasma-generated process may comprise a direct plasma-generated processin which plasma is directly generated in the reactor, or alternatively aremote plasma-generated process in which plasma is generated outside ofthe reactor and supplied into the reactor.

The silicon-containing precursors may be delivered to the reactionchamber such as a CVD or ALD reactor in a variety of ways. In oneembodiment, a liquid delivery system may be utilized. In an alternativeembodiment, a combined liquid delivery and flash vaporization processunit may be employed, such as, for example, the turbo vaporizermanufactured by MSP Corporation of Shoreview, Minn., to enable lowvolatility materials to be volumetrically delivered, which leads toreproducible transport and deposition without thermal decomposition ofthe precursor. In liquid delivery formulations, the precursors describedherein may be delivered in neat liquid form, or alternatively, may beemployed in solvent formulations or compositions comprising same. Thus,in certain embodiments the precursor formulations may include solventcomponent(s) of suitable character as may be desirable and advantageousin a given end use application to form a film on a substrate.

In certain embodiments, the gas lines connecting from the precursorcanisters to the reaction chamber are heated to one or more temperaturesdepending upon the process requirements and the container of the atleast one silicon-containing precursor is kept at one or moretemperatures for bubbling. In other embodiments, a solution comprisingthe at least one silicon-containing precursor is injected into avaporizer kept at one or more temperatures for direct liquid injection.

In a typical ALD or CCVD process, the substrate such as a silicon oxidesubstrate is heated on a heater stage in a reaction chamber that isexposed to the silicon-containing precursor initially to allow thecomplex to chemically adsorb onto the surface of the substrate. A purgegas such as argon purges away unabsorbed excess complex from the processchamber. After sufficient purging, a nitrogen-containing source may beintroduced into reaction chamber to react with the absorbed surfacefollowed by another gas purge to remove reaction by-products from thechamber. The process cycle can be repeated to achieve the desired filmthickness.

The rate of the deposition of the silicon-containing films can be in therange of 0.1 nm to 5000 nm per minute. The rate can be controlled byvarying any one of the following non-limiting parameters: depositiontemperature, the vaporizer temperature, the flow of the LFC, the flowrate of the reactive of O₂ gas and/or the pressure at the CVD reactor.Choice of precursor can also determine the deposition rate.

The resultant films or coatings may be exposed to a post-depositiontreatment such as, but not limited to, a plasma treatment, chemicaltreatment, ultraviolet light exposure, electron beam exposure, and/orother treatments to affect one or more properties of the film.

In the method described herein, it is understood that the steps of themethods described herein may be performed in a variety of orders, may beperformed sequentially or concurrently (e.g., during at least a portionof another step), and any combination thereof. The respective step ofsupplying the precursors and the nitrogen-containing source gases may beperformed by varying the duration of the time for supplying them tochange the stoichiometric composition of the resulting dielectric film.

In certain embodiments, passivation layers 1 and 2, shown in FIG. 9b as130 and 140 respectively, are deposited using the samesilicon-containing precursor. The silicon-containing films forpassivation layer 1 comprise silicon and nitrogen which is formed in thepresence of nitrogen-containing source. An nitrogen-containing sourcemay be introduced into the reactor in the form of at least one nitrogensource and/or may be present incidentally in the other precursors usedin the deposition process. The silicon-containing films for passivationlayer 2 comprise silicon and oxygen which is deposited using the methodsdescribed above in the presence of oxygen using an oxygen source,reagent or precursor comprising oxygen.

In certain embodiments, it may be advantageous to deposit a gradiatedlayer or a bilayer which is gradiated from top to bottom comprising SiCOor SiO₂ at the bottom and a SiNC or Si₃N₄ at the top. In thisembodiment, the gradiated layer is deposited from a first reagentmixture comprising a silicon containing precursor and a oxygencontaining precursor, such as, trisilylamine and O₂, ozone, or N₂O, andthen replacing the flow of the oxygen containing gas with an nitrogencontaining gas, such as, N₂, ammonia, or hydrazine. If the siliconcontaining precursor already contains nitrogen then the second step maybe performed using just an inert gas or hydrogen. The changing of theoxygen to nitrogen containing or inert gases can be gradual or abruptresulting in either a gradiated layer or a bilayer structure. Suchgradiated layer or a bilayer is advantageous as the SiOC layer protectsthe underlying layer from hydrogen generated during the deposition ofthe SiCN layer, while the SiCN layer acts as a moisture barrier in thefinal device. The silicon precursor for this embodiment would notcontain oxygen as the oxygen from the precursor is difficult to preventfrom incorporating into the SiCN or Si₃N₄ film.

The temperature of the reactor or deposition chamber for the depositionmay range from one of the following endpoints: ambient temperature 25°C.; 50° C.; 75° C.; 100° C.; 125° C.; 150° C.; 175° C.; 200° C.; 225°C.; 250° C.; 300° C.; 325° C.; 350° C.; 375° C.; 400° C.; and anycombinations thereof. In this regard, the temperature of the reactor ordeposition chamber for the deposition may range from ambient temperature25° C. to about 400° C., 100° C. to 370° C., 150° C. to 325° C., or 100°C. to 300° C., or any combinations of the temperature end-pointsdescribed herein.

The pressure of the reactor or deposition chamber may range from about0.1 Torr to about 1000 Torr. The respective step of supplying theprecursors, the oxygen source, and/or other precursors, source gases,and/or reagents may be performed by changing the time for supplying themto change the stoichiometric composition of the resulting dielectricfilm.

The following examples illustrate the method for preparing a dielectricfilm described herein and are not intended to limit it in any way.

EXAMPLES

General Deposition Conditions

The silicon containing films were deposited onto medium resistivity(8-12 Ωcm) single crystal silicon wafer substrates. In certain examples,the substrate may be exposed to a pre-deposition treatment such as, butnot limited to, a plasma treatment, chemical treatment, ultravioletlight exposure, electron beam exposure, and/or other treatments toaffect one or more properties of the film. For example, it may beadvantageous b subject the IGZO film to a N₂O, O₂, or O₃ plasmatreatment or an O₃ chemical treatment to ensure complete oxidation ofthe IGZO. This allows for the semiconducting properties to be preservedor enhanced prior to film deposition.

All depositions were performed on an Applied Materials Precision 5000system in a 200 mm DXZ chamber fitted with an Astron EX remote plasmagenerator, using either a silane or a TEOS process kit. The PECVDchamber is equipped with direct liquid injection delivery capability.With the exception of silane, all precursors were liquids with deliverytemperatures dependent on the precursor's boiling point. Typical liquidprecursor flow rates ranged from 100 to 800 mg/min, the plasma powerdensity ranged from 0.75 to 2.5 W/cm², and the pressure range was from0.75 to 8 torr. The thickness of the films and refractive index (RI) at632 nm were measured by a reflectometer. Typical film thickness for allabove analysis ranged from 100 to 1000 nm. In general, RI was not asensitive indicator of film properties in this study. —Bondingproperties of the silicon-containing were analyzed with a Nicolettransmission Fourier transform infrared spectroscopy (FTIR) tool. Alldensity measurements were accomplished using X-ray reflectivity (XRR).X-ray Photoelectron Spectroscopy (XPS) and Rutherford BackscatteringSpectrometry (RBS) were performed to determine the film composition. Wetetch rate (WER) was measured in a 10:1 Buffered Oxide Etch (BOE)solution. A mercury probe was utilized for all film measurements wheredielectric constant, electrical leakage and breakdown field arepresented. A Sinton WCT-120 Quasi Steady State Photoconductive Decaytool was used to measure minority carrier lifetimes in Float Zone HighResistivity Silicon with the minority carrier concentration of 5×10¹⁴and 1×10¹⁵ cm⁻³.

Silicon precursors were screened using a design of experiment (DOE)methodology summarized below: precursor flow from 100 to 800 mg/min;NH₃/He flow from 100 sccm to 1000 sccm, pressure from 0.75 to 8 torr; RFpower (13.56 MHz) 400 to 1000 W; Low-frequency (LF) power 0 to 100 W;and deposition temperature ranged from 150 to 350° C. The DOEexperiments were used to determine what process parameters produced theoptimal film for use as a passivation layer in a display device.

IGZO films were prepared by sputtering from an IGZO target using a KurtLesker Sputtering System with the wafer temperature less than 100° C.The sputtering pressure was around 6 mTorr with 10% oxygen and 90% argonas the gas mixture. The wafers were then annealed at 350° C. in N₂ambient atmosphere for 2 hours. A Signatone four-point probe was used toestimate the sheet resistance after annealing. The sheet resistivitybefore and after annealing was measured by Keithley 6517A electrometer &8009 fixture (with concentric ring electrodes contact).

Example 1: Deposition of Silicon-Containing Films Using Trisilylamine(TSA) and Ammonia (NH₃)

A number of silicon-containing films were deposited using trisylamine(USA) as precursor onto a 8 inch silicon substrate to see if any of thefilms would be suitable passivation layers in terms of density andhydrogen content. The composition of the films were measured by XPS andRBS/HFS and showed that the films were comprised of SixNy:Hz wherein theamount of silicon, nitrogen, and hydrogen or x, y, and z varied inatomic percentage depending upon the film. FIG. 1 shows the densityversus H-content relationship for these barrier films deposited usingTSA precursor.

Of the films deposited by TSA and shown in FIG. 1, the processconditions used to deposit the silicon-containing films having thehighest density and lowest hydrogen content using TSA were as followsTSA flow (100-200 mgm), NH₃ flow (100 sccm), He (1000 sccm), Pressure (2torr), RF (400 W), LF (0-100 W), and Temp (300° C.). Of the films shownin FIG. 1, the process conditions that produced the best TSA films inthe data set had densities and hydrogen content of 2.4-2.5 g/cm³ and2.0×10²² to 2.2×10²² cm⁻³, respectively.

For those data points shown in FIG. 1, FIG. 2 shows the relationshipbetween density (left x-axis), deposition temperature (y-axis), andH-content (right x-axis) for various TSA deposited-films deposited attemperatures ranging from 200 to 300° C. The square data pointsrepresent the H-content and the diamond data points represent thedensity for each film deposited at three different depositiontemperatures (e.g., 200, 250 and 300° C.). FIG. 2 generally shows thatthe density decreases as the H-content increases.

FIG. 3 shows the relationship between density and H-content for variousTSA-deposited films all of which were deposited at 300° C. The datapoints represented by the diamonds and squares represents differentprocess conditions. The diamond datapoints had no LF power whereas thesquare data points had LF power applied. The data shows that thedepositions where LF power was applied generally had lower H content.

Comparative Example 2: Deposition of Silicon-Containing Films UsingDimethyldiethoxysilane (DMDES)

Silicon-containing films were deposited using dimethyldiethoxysilame(DMDES) as precursor. The composition of the films were measured by XPSand showed that the films were comprised of SixCyOa:Hz wherein theamount of silicon, carbon, oxygen and hydrogen or x, y, a, and z variedin atomic percentage depending upon the film. FIG. 1 shows the densityversus H-content relationship for these silicon-containing filmsdeposited using the DMDES precursor.

The process parameters that produced the highest density and lowesthydrogen content film shown in FIG. 1 using the DMDES precursor were thefollowing: DMDES flow (200 mgm), H₂ flow (1000 sccm), He (300 sccm),Pressure (2 torr), RF (400 W), LF (100 W), and temperature (300° C.).Density and H-content for these films under these conditions were 2.0g/cm³ and 1.6×10²² cm⁻³, respectively. The DMDES deposited films did nothave the requisite density or hydrogen content to be an optimalpassivation layer for a display device comprising a metal oxide layercompared to the TSA deposited films.

Comparative Example 3: Deposition of Silicon-Containing Films UsingDi-Isopropylaminosilane (DIPAS)

Silicon-containing films were deposited using di-isopropylaminosilane(DIPAS) as precursor. The films were analyzed by XPS and showed thatthey were comprised of SixCyNa:Hz wherein the amount of silicon, carbon,nitrogen and hydrogen or x, y, a, and z varied in atomic percentagedepending upon the film. FIG. 1 shows the density versus H-contentrelationship for these silicon-containing films deposited using theDIPAS precursor.

The process parameters that produced the highest density and lowesthydrogen content film shown in FIG. 1 using the DIPAS precursor were thefollowing: DIPAS flow (200 mgm), NH₃ flow (500 sccm), He (300 sccm),Pressure (2 torr), RF (800 W), LF (0 W), and temperature (300° C.).Density and H-content form the SiCNH films under these conditions were2.3 g/cm³ and 3.1×10²² cm⁻³, respectively. The DIPAS deposited films didnot have the requisite density or hydrogen content to be an optimalpassivation layer for a display device comprising a metal oxide layercompared to the TSA deposited films.

Comparative Example 4: Deposition of Silicon-Containing Films Using 1,4Disiliabutane

Silicon-containing films were deposited using 1,4 disilabutane asprecursor. The films were analyzed by XPS and showed that they werecomprised of SixCyNa:Hz wherein the amount of silicon, carbon, nitrogenand hydrogen or x, y, a, and z varied in atomic percentage dependingupon the film. FIG. 1 shows the density versus H-content relationshipfor these silicon-containing films deposited using the 1,4 disilabutaneprecursor.

The process parameters that produced the highest density and lowesthydrogen content film shown in FIG. 1 using the 1,4 silabutane precursorwere the following: 1,4 disilabutane flow (200 mgm), NH₃ flow (500sccm), He (300 sccm), Pressure (2 torr), RF (1000 W), LF (100 W), andtemperature (300° C.). Density and H-content fom the SiCNH films underthese conditions were 2.3 g/cm³ and 2.95E22 cm⁻³, respectively. The 1,4disilabutane deposited films did not have the requisite density orhydrogen content to be an optimal passivation layer for a display devicecomprising a metal oxide layer compared to the TSA deposited films.

Comparative Example 5: Deposition of Silicon-Containing Films Using aMixture of TSA and Tri-Dimethylaminosilane (tDMAS)

Silicon-containing films were deposited using a mixture of TSA andtri-dimethylaminosilane (tDMAS) as precursor in varying ratios: 0, 0.60,1.00 and 1.67. The films were analyzed by XPS and showed that they werecomprised of SixCyNa:Hz wherein the amount of silicon, carbon, nitrogenand hydrogen or x, y, a, and z varied in atomic percentage dependingupon the film. FIG. 1 shows the density versus H-content relationshipfor these silicon-containing films deposited using the mixture of theTSA and tDMAS precursor.

The process parameters that produced the highest density and lowesthydrogen content film shown in FIG. 1 using the TSA-tDMAS mixture werethe following: TSA flow (150 mgm), tDMAS flow (250 mgm), H₂ flow (300sccm), He (1000 sccm), Pressure (4 torr), RF (600 W), LF (0 W), andtemperature (300° C.). Density and H-content form the SiCNH films underthese conditions were 1.9 g/cm³ and 3.7×10²² cm^(−3,) respectively.Referring to FIG. 1, the TSA-tDMAS deposited films had lower density andhigher hydrogen content metal oxide layer compared to the TSA depositedfilms and the tDMAS-H₂ deposited films. Further, while the tDMAS-NH₃films had higher densities, their hydrogen content was also relativelyhigher.

Comparative Example 6: Deposition of Silicon-Containing Films UsingTri-Dimethylaminosilane (tDMAS) and Ammonia as Diluent

Silicon-containing films were deposited using a tri-dimethylaminosilane(tDMAS) as precursor and NH₃ as a diluent using the general depositionconditions described above. The films were analyzed by XPS and showedthat they were comprised of SixCyNa:Hz wherein the amount of silicon,carbon, nitrogen and hydrogen or x, y, a, and z varied in atomicpercentage depending upon the film. FIG. 1 shows the density versusH-content relationship for these silicon-containing films depositedusing the mixture of the tDMAS precursor and NH₃ as a diluent. Referringto FIG. 1, the tDMAS-NH₃ deposited films did not have the requisitedensity or hydrogen content to be an optimal passivation layer for adisplay device comprising a metal oxide layer compared to the TSAdeposited films.

Comparative Example 7: Deposition of Silicon-Containing Films UsingTri-Dimethylaminosilane (tDMAS) and Hydrogen as Diluent

Silicon-containing films were deposited using a mixture oftri-dimethylaminosilane (tDMAS) as precursor and H₂ as the diluentsusing the general deposition conditions described above. The films wereanalyzed by XPS and showed that they were comprised of SixCyNa:Hzwherein the amount of silicon, carbon, nitrogen and hydrogen or x, y, a,and z varied in atomic percentage depending upon the film. FIG. 1 showsthe density versus H-content relationship for these silicon-containingfilms deposited using the mixture of the tDMAS precursor and H₂ as adiluent Referring to FIG. 1, the tDMAS-H₂ deposited films did not havethe requisite density or hydrogen content to be an optimal passivationlayer for a display device comprising a metal oxide layer compared tothe TSA deposited films. Further, the tDMAS-H₂ deposited films did notperform as well as the tDMAS-NH₃ deposited films.

Example 8: Comparison of Moisture Barrier Performance for SiliconContaining Layers Deposited Using TEOS and TSA Passivation Layers

In order to evaluate the relative moisture barrier performance of thesilicon-containing films deposited in the above examples, a test wasdeveloped to measure this property. In this test, a less dense silicondioxide (SiO₂) layer is first deposited using TEOS at 250° C. onto asilicon wafer under process conditions which render the film sensitiveto moisture. When such films are exposed to atmospheric moisture, oralternatively for this comparative test an accelerated test which usesan atmosphere of 85% humidity at 85° C., the film stress changes fromtensile to compressive. In this example and in FIG. 6, the dense TEOSand dense TSA films were compared to evaluate their relative moisturebarrier performance. Both films were deposited on the less dense TEOSoxide film.

To measure barrier performance, a thin layer of an exemplarysilicon-containing film is deposited on top of the moisture sensitiveSiO₂ layer and the stress of the film stack is measured in intervals ofexposure to the accelerated 85% humidity, 85° C. and then in ambientconditions (e.g., air). The wafers were placed in a 85% humidity and 85°C. oven. The stress measurement was conducted in air. As shown in FIG.5, all of the films deposited from TSA and NH₃ or wafers 6, 7, and 8,had a film density of 2.52 g/cm³, and would provide the best passivationor barrier layer thereby not allowing any moisture into the underlyinglayer as evidenced by little if any change in the stress of the filmstack.

FIG. 4 provides a comparison of the stress measured in (MPa) and time(hours) for 100 nm thick passivation layers comprised of the following:(A) (shown as diamonds on Figure) trisilylamine and NH₃ (density=2.36g/cm³); (B) (shown as triangles on Figure) di-isopropylaminosilane andNH₃; (C) (shown as squares on the Figure) dimethyldiethoxysilane and H₂(density=1.95 g/cm³); and (D) (shown as circles on the Figure)trimethylsilane and NH₃ (density=1.88 g/cm³). The SiCN film, which wasdeposited from trimethylsilane and ammonia, shown as line (D) on theFigure, and has a density of 1.88 g/cm³, did not exhibit a barrierperformance as good as TSA as evidenced by a steep drop in the filmstress (without a barrier in place the film stress drops from 250 tominus 100 MPa in the first 1 hour). The SiOC barrier film deposited fromdimethyldiethyoxysilane and H₂ and has a density of 1.95 g/cm³ and shownas line (C) on the Figure falls between the TSA films and the DMDESfilms in terms of barrier performance. The SiCN films deposited fromDIPAS and NH₃ exhibit barrier performance similar to the film depositedfrom DMDES and H₂ and had a density of 2.11 g/cm³. Additional teststructures comprising a dual passivation layer structure comprising asilicon oxide layer deposited using TEOS and a silicon nitride layerdeposited using TSA such as the structure shown in FIG. 6. The thicknessof the TEOS-deposited silicon oxide layer was 850 nm and the thicknessof the TSA-deposited silicon nitride layer was either 50 nm or 100 nm.The deposition conditions for test wafer 3 which had a 50 nmTSA-deposited silicon nitride was a power of 800 W, a pressure of 2Torr, the flow rate of TSA 100 (mg/min.), a flow rate of helium of 1,000sccm, a flow rate of ammonia of 100 sccm, and a deposition temperatureof 100° C. The density of the TSA layer for test structure 3 was 2.342g/cm^(3.) All of the test structures 50 nm and 100 nm were deposited inthe same manner and have the same density that are shown in FIG. 10. Thestructures were subjected to accelerated weather testing which isindicative of hermeticity as described in this Example and the resultsare provided in FIG. 10. FIG. 10 shows that the test structures whichhad a thicker silicon nitride passivation layer or 100 nm layer weremore stable and therefore had better hermeticity than structures havinga thinner or 50 nm layer.

Example 9: Evaluation of the Effect of Thickness of PECVD Silicon OxideAtop In—Ga—Zn—O (IGZO) Metal Oxide Film Wherein Silicon Oxide LayerFurther Topped with Silicon

Nitride Layer

FIG. 6 provides an exemplary structure of a display device comprising aIGZO metal oxide layer 610, a plasma-enhanced chemical vapor deposition(PECVD) silicon oxide layer 630 deposited by tetraethoxysilane (TEOS),and a silicon nitride layer 640 deposited by TSA and NH₃ to provide adensity silicon nitride a 2.36 g/cm³. The thickness of the silicon oxidelayer 630 was varied from 0 to 250 nanometers (e.g., 15 nm, 60 nm, 115nm, 185 nm, 200 nm, and 250 nm) to determine its impact on minoritycarrier lifetime. The thickness of the TSA silicon nitride layer wasapproximately 100 nm. The films were deposited according to the generaldeposition conditions described above and the following processconditions: (1) TEOS: Power=910 W, Pressure=8.2 Torr, TEOS flow=1000mg/min, O₂ flow=1000 sccm, He flow=1000 sccm; and (2) TSA: Power=400 W,Pressure=4 Torr, TSA flow=200 mg/min, NH₃ flow=100 sccm, He flow=1000sccm.

FIG. 7 shows the impact of film thickness on the minority carrierlifetime in Float Zone high resistivity silicon (1000 Ω-cm) which wasmeasured at two different levels of carrier injectors thereby producingthe two lines of data shown in FIG. 7 (e.g., 1.00×10⁻¹⁵ and 5.00×10⁻¹⁴cm⁻³). At thin or no silicon oxide thicknesses, the hydrogen from thesilicon nitride film diffuses to the surface of the silicon substrateand passivates surface defects thereby reducing the surfacerecombination velocity and thereby increases the minority carrierlifetimes. As the thickness of the silicon oxide layer is increased,hydrogen diffusion through the oxide film is reduced and the minoritycarrier lifetime is subsequently reduced. FIG. 7 shows that thepreferred thickness to minimize hydrogen diffusion through the siliconoxide film ranges from about 150 to about 200 nm because the curve onthe figure is flat when the thickness is 150 nm or greater. Thisthickness is sufficient to prevent hydrogen diffusion through the film.Films that are too thick may not be desirable from the perspective ofthe end user.

Example 10: Comparison of Passivation Layer Structure on IGZOResistivity

The ability of silicon oxide to serve as a barrier to hydrogen diffusionfrom silicon nitride was evaluated on a metal oxide or IGZO substrate bycomparing various passivation layer structures as shown in FIGS. 8athrough 8f . The layered structures consisted of depositing siliconnitride films on a silicon substrate followed by depositing siliconoxide followed by sputtering of approximately 50 nm of IGZO as describedabove in the General Deposition Conditions. The film stack was exposedto a thermal anneal of 350° C. in an inert ambient for two hours asdescribed herein. The subsequent resistivity of the film was measured todetermine the degree to which the resistivity of the IGZO metal oxidewas reduced. Table I provides the comparative data for the layeredstructures depicted in FIGS. 8a through 8e and are referred to asExamples 10a through 10 f.

Example 10a

A Si wafer substrate (810) upon which a 100 nm thermal oxide (820) wasgrown followed by sputtering 50 nm of amorphous IGZO (830) on itssurface as depicted in FIG. 8a and was annealed at 350° C. for two hoursin an inert (N₂) atmosphere. The post anneal resistance was measured anddetermined to be 1.1×10⁵Ω/□.

Example 10b

A Si wafer substrate (810) upon which a 200 nm PECVD silicon oxide layer(822) was deposited using TEOS, followed by a 100 nm PECVD siliconnitride layer from TSA precursor (825) and having a density of 2.52g/cm³, followed by 50 nm of amorphous IGZO (830) sputtered on itssurface as shown in FIG. 8b and was annealed at 350° C. for two hours inan inert (N₂) atmosphere. The post anneal resistance was measured anddetermined to be 1.9×10³Ω/□.

Example 10c

A Si wafer substrate (810) upon which a 200 nm PECVD silicon oxide layer(822) was deposited using TEOS, followed by a 100 nm PECVD siliconnitride layer from TSA precursor (825) and having a density of 2.52g/cm³, followed by a 100 nm of PECVD Silicon Oxide (828) layer depositedusing TEOS precursor, followed by 50 nm of amorphous IGZO (830)sputtered on its surface as shown in FIG. 8c and was annealed at 350° C.for two hours in an inert (N₂) atmosphere. The post anneal resistancewas measured and determined to be 3.9×10³Ω/□.

Example 10d

A Si wafer substrate (810) upon which a 200 nm PECVD silicon oxidebuffer was deposited (822), followed by a 100 nm PECVD silicon nitridelayer from TSA precursor (825) and having a density of 2.52 g/cm³,followed by a 200 nm of PECVD Silicon Oxide (828) layer deposited usingTEOS precursor, and followed by 50 nm of amorphous IGZO (830) sputteredon its surface as shown in FIG. 8c and was annealed at 350° C. for twohours in an inert (N₂) atmosphere. The post anneal resistance wasmeasured and determined to be 1.1×10⁴ Ω/cm. Example 10d differs fromExample 10c in that the PECVD silicon oxide layer 828 is twice as thickor 200 nm as comparable layer 828 in Example 10c.

Example 10e

A Si wafer substrate (810) upon which a 200 nm PECVD silicon oxide layer(822) was deposited using TEOS at 400° C., followed by a 200 nm of PECVDTEOS based Silicon Oxide (828), followed by 50 nm of amorphous IGZOsputtered (830) on its surface as shown in FIG. 8d and was annealed at350° C. for two hours in an inert (N₂) atmosphere. The post annealresistance was measured and determined to be 1.0×10⁴Ω/□.

Example 10f

A Si wafer substrate (810) upon which a 200 nm PECVD silicon oxide layer(822) was deposited, followed by a 100 nm silane based PECVD siliconnitride layer (840), followed by a 200 nm of PECVD silane based SiliconOxide (848), followed by 50 nm of amorphous IGZO sputtered (830) on itssurface as shown in FIG. 8e and was annealed at 350° C. for two hours inan inert (N₂) atmosphere. The post anneal resistance was measured anddetermined to be 3.9×10³Ω/□.

Referring to Table I, example 10a, or the structure shown in FIG. 8a ,shows a thermal silicon oxide alone and represents the case of thehighest purity silicon oxide containing an Oxygen to Silicon ratio ofclose to 2.0 or a fully stoichiometric SiO₂ film. This oxide had thelowest impact on resistivity of the IGZO film. Structures having nosilicon oxide passivation layers, or Example 10b (structure depicted inFIG. 8b ), was found to have the greatest reduction in IGZO sheetresistance from 1.1×10⁵ to 1.9×10³Ω/□. Films with 100 or 200 nm siliconoxide thicknesses or Examples 10c and 10d showed reduced reduction inIGZO resistivity. The film with PECVD silicon oxide and no siliconnitride passivation layer or Example 10e (structure depicted in FIG. 8d) showed a comparable reduction in resistivity to the 200 nm siliconoxide/silicon nitride film stack, suggesting an effective barrier tohydrogen diffusion but also indicating some contribution to thereduction in IGZO resistance from the PECVD silicon oxide film relativeto the thermal oxide. Table 1 also provides the results obtained whichused both silane gas as precursor for both silicon oxide and nitride inExample 10f (structure depicted in FIG. 8e ), which is the currentindustry standard and is used, for example, in the Liu et al referencedescribed herein. Example 10f shows that the selection of thepassivation layer(s) is important because the metal oxide does notremain in a semiconductive state (e.g., having a resistance measurementbetween 1×10⁴ and 1×10⁵ (Ω/□)) to be effective as a display device.Results indicated less impact on IGZO resistance for an optimizedorganosilane based oxide relative to a silane based oxide at 300° C.

TABLE I Impact of Film Stack Composition on IGZO Sheet Resistance.Resistance Film Stack (Ω/□) Example 10a: Si/Thermal Silicon Oxide/IGZO1.1 × 10⁵ Example 10b: Si/PECVD Silicon Nitride/IGZO 1.9 × 10³ Example10c: Si/PECVD Silicon Nitride/100 nm PECVD 3.9 × 10³ Silicon Oxide/IGZOExample 10d: Si/PECVD Silicon Nitride/200 nm PECVD 1.1 × 10⁴ SiliconOxide/IGZO Example 10e: Si/PECVD 200 nm Silicon Oxide/IGZO 1.0 × 10⁴Example 10f: Si/PECVD Silicon Nitride (SiH₄)/Silicon Oxide 3.9 × 10³(SiH₄)/IGZO

Example 11: Deposition of Thin SiO₂ Films Using Triethylsilane (3ES)with High Density

Process conditions for the 3ES silicon oxide films were screened using adesign of experiment (DOE) methodology summarized below: precursor flowfrom 100 to 800 sccm; O₂/He flow from 20 to 100 sccm, pressure from 0.75to 10 torr; RF power (13.56 MHz) 0.5-3 W/cm²; Low-frequency (LF) power 0to 100 W; and deposition temperature ranged from 100° C. to 150° C. TheDOE experiments were used to determine what process parameters producedthe optimal film for use as a gate insulating layer in a display device.

SiO₂ films were deposited using the precursor 3ES at lower depositiontemperatures, such as 100° C., 125° C. and 150° C. then described above.By optimizing the process parameters, such as precursor flow, chamberpressure and power density, etc., high density and thin SiO₂ films wereobtained. Table II shows a summary of the three process conditions usedfor 3ES film deposited at different temperatures 100° C., 125° C. and150° C., as well as certain film properties, such as thickness, k valueand density which were measured using the methods described herein inthe general deposition conditions. In general, the films deposited using3ES had a thickness less than 200 nm, a k value between 4 to 5, and adensity of 2.2 g/cm³ or greater. This example shows that 3ES is asuitable precursor candidate to provide a high density silicon oxidelayer which can be used, for example, as an additional passivation layeralong with a TSA-deposited silicon nitride passivation layer such asthose embodiments illustrated, for example, in FIG. 9b .

TABLE II Summary of process conditions used for 3ES film deposited atdifferent temperatures 100° C., 125° C. and 150° C. and the filmproperties Process conditions 3ES 100° C.  3ES 125° C.  3ES 150° C. Precursor flow 27 48 27 (sccm) He (carrier, sccm) 1000 1000 1000 O₂(sccm) 1000 1000 1000 Pressure (torr) 9.2 9.2 9.2 Spacing (mils) 500 500500 Power density 1.75 2.5 2.5 (W/cm²) Film thickness (nm) 165 113 173Film Density (g/cm³) 2.26 2.29 2.28 K value 4.67 4.62 4.42

Example 12: Deposition of Thin SiO₂ Films Using Diethylsilane (2ES) withHigh Density

Process conditions for the 2ES silicon oxide films were screened attemperatures below 200° C. using a design of experiment (DOE)methodology summarized below: typical precursor flow rates were 25 to150 sccms, plasma power density was 0.5-3 W/cm², and pressure was0.75-12 torr.

The SiO₂ films were also deposited at a deposition temperature of 100°C. using 2ES. By optimizing the process parameters, such as precursorflow, chamber pressure and power density, and other process conditions,high density and thin SiO₂ films were obtained. Table III shows asummary of the process conditions used for 2ES film deposited at 100° C.as well as the certain film properties, such as thickness, k value anddensity which were obtained using the methods described herein. The filmhad a thickness less than 200 nm and a density higher than 2.2 g/cm³.This example shows that 2ES is a suitable precursor candidate to providea high density silicon oxide layer which can be used, for example, as anadditional passivation layer along with a TSA-deposited silicon nitridepassivation layer such as those embodiments illustrated, for example, inFIG. 9b .

TABLE III Summary of process conditions used for 2ES-deposited SiO2 filmat 100° C. and film properties. Process conditions 2ES 100° C. Precursorflow (sccm) 38 He (carrier, sccm) 1000 O₂ (sccm) 1000 Pressure (Torr) 10Spacing (mils) 500 Power density (W/cm²) 1.5 Film thickness (nm) 195Density (g/cm³) 2.21 K value 5.05

Example 13: Deposition of Thin SiO₂ Films Using 3ES at 100° C. with HighDensity

The present example is used to show the deposition of thin and highdensity SiO₂ film using 3ES provides a wide process window. Table IVprovides the process conditions for two 3ES deposited, SiO₂ films andfilm properties at different precursor flow, 29 sccm and 68 sccm.Although the table shows a wide range of deposition rates, high densityfilms were obtained. This example shows that 3ES is a suitable precursorcandidate to provide a high density silicon oxide layer which can beused, for example, as an additional passivation layer along with aTSA-deposited silicon nitride passivation layer such as thoseembodiments illustrated, for example, in FIG. 9b .

TABLE IV Summary of Process Conditions for 100° C. 3ES DepositionsProcess conditions 100° C. 100° C. Precursor flow (sccm) 29 68 He(carrier, sccm) 1000 1000 O₂ (sccm) 1000 1000 Pressure (Torr) 9.2 9.2Spacing (mils) 500 500 Power density (W/cm²) 2.5 2.5 Deposition rate(nm/min) 27 89 Film thickness (nm) 160 222 K value 4.77 5.07 Density(g/cm³) 2.26 2.23

Example 14: Compositional Data of Thin SiO₂ Films Deposited Using 3ES at100° C. and 150° C.

XPS was used to exam the carbon concentration in the film. The relativeatomic percentage is measured at the surface and after 50 nm sputtering.Table V shows the process conditions and film properties of two 3ESfilms deposited at 100° C. and 150° C. Table VI provides the XPS data ofthe films. No carbon was detected in the bulk film and the O/Si ratio ofthe film was very close to 2.0 or stoichiometric. This example showsthat 3ES is a suitable precursor candidate to provide a high densitysilicon oxide layer which can be used, for example, as an additionalpassivation layer along with a TSA-deposited silicon nitride passivationlayer such as those embodiments illustrated, for example, in FIG. 9b .

TABLE V Summary of process conditions and film properties of 3ES films.Process conditions 3ES 150° C. 3ES 100° C. Precursor flow (sccm) 68 50He (carrier, sccm) 1000 1000 O₂ (sccm) 1000 1000 Pressure (Torr) 9.2 9Spacing (mils) 500 700 Power density (W/cm²) 2.5 2.0 Film thickness (nm)210 206 K value 4.69 4.84 Density (g/cm³) 2.248 2.27

TABLE VI XPS data of 3ES films deposited Using Table 5 ProcessConditions. Sample Relative Atomic Percent ID Location Condition O N CSi O/Si 3ES A As Received 62.0 ND 8.5 29.5 2.10 150° C. After 500 Å 66.8ND ND 33.2 2.01 Sputter B As Received 63.0 ND 9.4 27.7 2.28 After 500 Å67.3 ND ND 32.7 2.06 Sputter 3ES A As Received 57.5 ND 15.7  26.9 2.1100° C. After 500 Å 66.7 ND 33.3 2.0 Sputter B As Received 61.4 ND 9.429.3 2.1 After 500 Å 66.5 ND 33.5 2.0 Sputter

Example 15: Deposition of Diethylsilane (2ES) at Deposition Temperaturesof 250° C. and 350° C.

Silicon oxide films were deposited from the silicon precursor 2ES and3ES SiO₂ films were deposited at different temperature and processconditions using the general deposition conditions described above andthe following process conditions: precursor flow of 107 sccm; heliumcarrier gas flow of 1000 sccm; oxygen (O₂) gas flow of 1100 sccm,pressure of 8.2 torr; spacing of 500 mils, and power density of W/cm².

The H-content in atomic % and measured by RBS for the DES depositedfilms which were deposited at a above process conditions at depositiontemperature of 350° C. and 250° C. were 2.0% (density of 2.25 g/cm³) and2.8% (density of 2.26 g/cm³), respectively. This shows that both DESdeposited films had very low total hydrogen content (<5%) as measured byRBS/HFS. This is also confirmed by a FTIR analysis of these films whichshowed no detectible Si—H and very minimal Si—OH bonding. This exampleshows that 2ES is a suitable precursor candidate to provide a highdensity and low hydrogen content silicon oxide layer which can be used,for example, as an additional passivation layer along with aTSA-deposited silicon nitride passivation layer such as thoseembodiments illustrated, for example, in FIG. 9 b.

The examples and embodiments described herein, are exemplary of numerousembodiments that may be made. It is contemplated that numerous materialsother than those specifically disclosed may be made. Numerous otherconfigurations of the process may also be used, and the materials usedin the process may be elected from numerous materials other than thosespecifically disclosed.

The invention claimed is:
 1. A method for depositing asilicon-containing layer on a surface of a substrate, the methodcomprising: providing the substrate in a reaction chamber wherein thesubstrate comprises a transparent conductive metal oxide layer;depositing via a PECVD process a silicon oxide layer on top of thetransparent conductive metal oxide layer, wherein the silicon oxidelayer is deposited from a tetraethoxysilane precursor at a temperatureof from 80° C. to 400° C., and wherein the silicon oxide layer has athickness of from about 2 nm to 200 nm and a density of about 2.2 g/cm³or greater; depositing via a vapor deposition process a siliconcontaining-layer by i. introducing into the reaction chamber at leastone silicon precursor selected from the group consisting of:trisilylamine (TSA); a dialkylaminosilane having a formula of R¹R²NSiH₃wherein R¹ is independently selected from the group consisting of aC₁₋₁₀ linear or branched alkyl group; a C₄ to C₁₀ cyclic alkyl group; aC₃ to C₁₂ alkenyl group; a C₃ to C₁₂ alkynyl group; and a C₆ to C₁₀ arylgroup; R² is independently selected from a C₁₋₁₀ linear or branchedalkyl group; a C₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl group;a C₃ to C₁₂ alkynyl group; and a C₆ to C₁₀ aryl group and wherein R¹ andR² are linked to form a ring or R¹ and R² are not linked to form a ring;organoaminosilane having a formula of (R¹R²N)_(n)SiH_(4-n) wherein R¹ isindependently selected from the group consisting of a C₁₋₁₀ linear orbranched alkyl group; a C₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂alkenyl group; a C₃ to C₁₂ alkynyl group; and a C₆ to C₁₀ aryl group; R²is independently selected from a C₁₋₁₀ linear or branched alkyl group; aC₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂ alkenyl group; a C₃ to C₁₂alkynyl group; and a C₆ to C₁₀ aryl group and wherein R¹ and R² arelinked to form a ring or R¹ and R² are not linked to form a ring; and nis 2, 3, or 4; an isocyanatosilane selected from the group consisting oftetra(isocynato)silane and tri(isocynato)silane; an alkylazidosilaneshaving the formula of R¹R²R³SiN₃ wherein R¹, R², and R³ areindependently selected from the group consisting of a C₁₋₁₀ linear orbranched alkyl group; a C₄ to C₁₀ cyclic alkyl group; a C₃ to C₁₂alkenyl group; a C₃ to C₁₂ alkynyl group; and a C₆ to C₁₀ aryl group;ii. introducing into the reaction chamber a source selected from thegroup consisting of an oxygen source, a nitrogen-containing source, anda combination thereof; and iii. applying energy to the at least onesilicon precursor and the source to deposit the silicon containing layeron the at least one surface of the silicon oxide layer at one or moretemperatures ranging from about 25° C. to 350° C. to form a doublepassivation layer on top of the transparent conductive metal oxidelayer, wherein the vapor deposition process is selected from the groupconsisting of plasma enhanced chemical vapor deposition (PECVD), atomiclayer deposition (ALD), and plasma enhanced atomic layer deposition(PEALD), wherein the silicon containing layer comprises silicon nitridehaving a transparency of greater than about 90% at 400-700 nanometerswhen measured by UV-visible light spectrometry, and wherein the siliconnitride has a density of 2.4 g/cm³ or greater and a hydrogen content of4×10²² cm⁻³ or less.
 2. The method of claim 1 wherein the conductivemetal oxide layer comprises at least one selected from the groupconsisting of Indium Gallium Zinc Oxide (IGZO), a-IGZO (amorphous indiumgallium zinc oxide), Indium Tin Zinc Oxide (ITZO), Aluminum Indium Oxide(AlInOx), Zinc Tin Oxide (ZTO), Zinc Oxynitride (ZnON), Magnesium ZincOxide, zinc oxide (ZnO), InGaZnON, ZnON, ZnSnO, CdSnO, GaSnO, TiSnO,CuAlO, SrCuo, LaCuOS, and combinations thereof.
 3. The method of claim 1wherein the silicon oxide layer comprises a hydrogen content of 5 atomic% or less.
 4. The method of claim 1 wherein the silicon-containing layercomprises at least one or more of the following properties: a densitygreater of about 1.9 g/cm³ or greater, a hydrogen content of 4×10²² cm⁻³or less, and a transparency >90% at 400-700 nm.
 5. The method of claim 1wherein the oxygen source is selected from the group consisting of water(H₂O), oxygen (O₂), oxygen plasma, ozone (O₃), NO, N₂O, carbon monoxide(CO), carbon dioxide (CO₂) and combinations thereof.
 6. The method ofclaim 1 wherein the nitrogen-containing source is selected from thegroup consisting of ammonia, hydrazine, monoalkylhydrazine,dialkylhydrazine, nitrogen, nitrogen/hydrogen, ammonia plasma, nitrogenplasma, nitrogen/hydrogen plasma, NF₃, and mixtures thereof.
 7. Themethod of claim 1 wherein the temperature of the depositing step rangesfrom about 150° C. to about 350° C.
 8. The method of claim 1 wherein thevapor deposition process is plasma enhanced chemical vapor deposition(PECVD).
 9. The method of claim 1 wherein the silicon precursorcomprises trisilylamine.
 10. The method of claim 1 wherein thesilicon-containing layer comprises a single passivation layer.